/* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package java.nio;
import org.apache.harmony.luni.platform.PlatformAddress;
/**
* Helper class for operations on direct ByteBuffer
*
* @see java.nio.ByteBuffer
*/
class DirectByteBuffers {
/**
* Explicitly frees the memory used by the given direct byte buffer.
* <p>
* If the memory is known to already have been freed then this is a no-op.
* Once the memory has been freed then operations requiring access to the
* memory will throw an <code>IllegalStateException</code>.
* <p>
* Note this is is possible that the memory is freed by code that reaches
* into the address and explicitly frees it 'beneith' us -- this is bad
* form.
*
* @param directBuffer
* the direct byte buffer memory to free
* @throws IllegalArgumentException
* if the buffer is <code>null</code> or is not a
* <em>direct</em> byte buffer.
*/
public static void free(ByteBuffer directBuffer) {
if ((directBuffer == null) || (!directBuffer.isDirect())) {
throw new IllegalArgumentException();
}
DirectByteBuffer buf = (DirectByteBuffer) directBuffer;
buf.free();
}
/**
* Returns the platform address of the start of this buffer instance.
* <em>You must not attempt to free the returned address!!</em> It may not
* be an address that was explicitly malloc'ed (i.e. if this buffer is the
* result of a split); and it may be memory shared by multiple buffers.
* <p>
* If you can guarantee that you want to free the underlying memory call the
* #free() method on this instance -- generally applications will rely on
* the garbage collector to autofree this memory.
*
* @param directBuffer
* the direct byte buffer
* @return the effective address of the start of the buffer.
* @throws IllegalStateException
* if this buffer address is known to have been freed
* previously.
*/
public static PlatformAddress getEffectiveAddress(ByteBuffer directBuffer) {
return toDirectBuffer(directBuffer).getEffectiveAddress();
}
private static DirectByteBuffer toDirectBuffer(ByteBuffer directBuffer) {
if ((directBuffer == null) || (!directBuffer.isDirect())) {
throw new IllegalArgumentException();
}
return (DirectByteBuffer) directBuffer;
}
}